Stylus position system

ABSTRACT

A system of one embodiment includes a touch-sensing device and a stylus. The touch sensing device includes an electrode array, which includes a plurality of electrode line pairs, and a controller. Each electrode line pair includes a first and second electrode line to send a first and second signal, respectively. The stylus includes a sensor to measure the first and second signals, a signal processor to determine position information, and a transmitter to send position information to the touch-sensing device. 
     A method of another embodiment includes sending, by a first electrode line, a first signal having a first frequency. A second electrode line sends a second signal having a second frequency. A stylus receives the first and second signals. The stylus sends a response signal to the touch-sensing device based on the first and second signals. A position of the stylus is determined based on the first and second signals.

TECHNICAL FIELD

The present invention relates generally to the field of touch-sensingdevices and more particularly to a stylus position system.

BACKGROUND

Conventional touch-sensing devices may detect the presence and locationof a touch or the proximity of an object (such as a user's finger or astylus) within a touch-sensitive area. A touch-sensing device may be, ormay be associated with, a desktop computer, laptop computer, tabletcomputer, personal digital assistant (PDA), smartphone, satellitenavigation device, portable media player, portable game console, kioskcomputer, point-of-sale device, household appliance, or other suitabledevice.

Conventional touch-sensing devices may utilize different types oftouch-sensitive technologies such as, for example, resistivetouch-sensing devices, surface acoustic wave touch-sensing devices, andcapacitive touch-sensing devices. In capacitive touch-sensing devices,when an object touches or is brought in proximity to an electrode arrayof a touch-sensing device, a change in capacitance may occur within theelectrode array at the location of the touch or proximity. Thetouch-sensing device may then process the change in capacitance todetermine the position of the object.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and itsfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 illustrates an example touch-sensing system.

FIG. 2 illustrates an example stylus that may be used in a touch-sensingsystem.

FIG. 3 illustrates an example sender that may be used in a stylus.

FIG. 4 illustrates an example touch-sensing device that may be used in atouch-sensing system.

FIG. 5 illustrates an example electrode array that may be used in atouch-sensing device.

FIG. 6 illustrates an example measurement circuit that may be used in atouch-sensing device.

FIG. 7 illustrates an example stylus and electrode array that may beused in a touch-sensing system.

FIG. 8 illustrates relationships between an example stylus and electrodearray that may be used in a touch-sensing system.

DESCRIPTION OF EXAMPLE EMBODIMENTS

According to one embodiment, a method includes generating, by a stylus,a composite signal. The composite signal includes a first signal havinga first frequency, the first signal being used by a touch-sensing deviceto determine a position of the stylus relative to the touch-sensingdevice, and a second signal having a second frequency. The second signalincludes information indicating a status of the stylus, and the secondfrequency is higher than the first frequency, though in otherembodiments, the second frequency may be less than or equal to the firstfrequency. The information indicating the status of the stylus mayinclude battery information, orientation information, sensoryinformation (such as information indicating an amount of force exertedon the tip of the stylus, information indicating a status of a button ofthe stylus, etc.) information indicating input from a user of thestylus, and/or information indicating the distance between the tip ofthe stylus and the touch-sensing device. The stylus sends the compositesignal to the touch-sensing device. Utilizing a composite signal in thismanner may allow for the transmission of different types of statusinformation, such as battery status, stylus orientation, the stylus'sdistance from the touch-sensing device, and the amount of force exertedon a portion of the stylus, over the same components that are used todetect the position of the stylus. This may reduce the need foradditional transceiver hardware, allow for more efficient communicationbetween the stylus and the touch-sensing device, make communicationbetween the stylus and touch-sensing device less prone to noise, and/orincrease the throughput of data transmission. Various embodiments mayprovide some, all, or none of these benefits.

According to another embodiment, a system includes a touch-sensingdevice and a stylus. The touch sensing device includes an electrodearray and a controller configured to control the electrode array. Theelectrode array includes a plurality of electrode line pairs, and eachelectrode line pair includes a first electrode line configured to send afirst signal and a second electrode line configured to send a secondsignal. The stylus includes a sensor configured to measure the firstsignal and the second signal, a signal processor configured to determineposition information based at least on the first signal and secondsignal, and a transmitter configured to send a signal comprising theposition information to the touch sensing device. In certainembodiments, the first and second signals may be differentiated by usingquadrature phase-shifting, signal encoding, frequency modulation;amplitude modulation; phase modulation; or other suitable means fordifferentiating signals. This may allow the stylus to determine its ownposition, improve positional accuracy, and/or provide more efficientutilization of touch-sensing hardware. Various embodiments may providesome, all, or none of these benefits. Various embodiments may providesome, all, or none of these benefits.

In yet another embodiment, a method includes generating, by atouch-sensing device, a first signal comprising information identifyinga first electrode line of an electrode array of the touch-sensingdevice, the first signal having a first strength. The first electrodeline sends the first signal to a stylus, which receives the firstsignal, the first signal having a received strength. The stylus sends asecond signal comprising information based on the received first signal,and the touch-sensing device receives the second the second signal. Aposition of the stylus is determined based at least in part on theinformation identifying the first electrode line and the receivedstrength of the first signal. This signaling scheme may improve theability of stylus and finger-sensing to coexist and may also reduceinterference between finger-sensing and stylus-sensing that may occurwhen both utilize the same electrode array.

FIG. 1 illustrates an example touch-sensing system 20. Touch-sensingsystem 20 includes stylus 200 and touch-sensing device 100, which hastouch-sensitive area 104. Touch-sensing device 100 may be a tabletcomputer, smart phone, touchpad, or other device configured to detectthe presence of stylus 200 on or near touch-sensitive area 104.Touch-sensing device 100 may have a display (not shown) situated behindtouch-sensitive area 104. The display may be a liquid crystal display(LCD), an LED display, an LED-backlight LCD, or any other suitabledisplay, and the display may be visible through an electrode array (notshown) or a cover panel (not shown).

Stylus 200 may be an active stylus configured to communicate withtouch-sensing device 100. Stylus 200 may interact or communicate withtouch-sensing device 100 when brought in contact with or in proximity totouch-sensitive area 104. In certain embodiments, interaction betweenstylus 200 and touch-sensing device 100 may be capacitive or inductive.For example, in some embodiments, when stylus 200 is brought in contactwith or in proximity to touch-sensitive area 104, signals generated bystylus 200 may influence capacitive electrodes of touch-sensing device100, or signals generated by touch-sensing device 100 may influencecapacitive electrodes of stylus 200. In other embodiments, a powersource of stylus 200 may be inductively charged by touch-sensing device100, or a power source of touch-sensing device 100 may be charged bystylus 200. Other embodiments may utilize any suitable method ofinteraction and/or communication between stylus 200 and touch-sensingdevice 100 in place of or in addition to capacitance and induction, suchas mechanical forces, current, voltage, or electromagnetic fields. Thecapacitive coupling, inductive coupling, and other coupling mechanismsmay be utilized for a variety of purposes, such as detecting a positionof stylus 200 or a finger and communicating information between stylus200 and touch-sensing device 100.

FIG. 2 illustrates an example stylus 200 that may be used intouch-sensing system 20 from FIG. 1. Stylus 200 includes processor 210,sender 220, and receiver 260. In other embodiments, stylus 200 mayinclude processor 210 and sender 220, but not receiver 260. Processor210 may control sender 220 and receiver 260. Receiver 260 may beconfigured to detect a signal generated by touch-sensing device 100 (notshown). Sender 220 may be configured to generate a signal that isreceived by touch-sensitive device 100 and used to determine theposition of stylus 200 and/or information indicating a status of stylus200. For example, sender 220 may generate a drive signal that isdetected by touch-sensing device 100 and used to identify the positionof stylus 200. In some embodiments, the drive signal may be detected bya capacitive electrode array of touch-sensing device 100 as describedabove.

In some embodiments, sender 220 generates a composite signal containingboth the drive signal, which may be used to determine the position ofstylus 200, as well as a data signal that contains informationindicating a status of stylus 200. The status of stylus 200 may include,but is not limited to, the orientation of the stylus, whether a portionof the stylus is within a threshold distance of a portion oftouch-sensing device 100, sensory information (such as an amount offorce exerted on the tip of the stylus, a status of a button of thestylus, etc.) and/or the status of a battery. For example, stylus 200may encode the drive signal with information indicating the amount ofpressure on the tip of stylus 200. The composite signal may alsocommunicate the orientation of stylus 200, which may be based ongyroscopic information, or the distance of stylus 200 fromtouch-sensitive area 104, which may be used to determine whether stylus200 is in a “hover mode” with its tip positioned within a thresholddistance. In various embodiments, the composite signal may include some,all, or none of this information.

The composite signal may be detected by the same capacitive electrodearray of touch-sensing device 100 that is utilized to determine theposition of stylus 200. Communicating this status information totouch-sensing device 100 via electrode array 110 may reduce the need foradditional transceiver hardware, allow for more efficient communicationbetween the stylus and the touch-sensing device, make communicationbetween the stylus and touch-sensing device less prone to noise, and/orincrease the throughput of data transmission.

Sender 220 may also send information to touch-sensing device 100 via awireless transmitter. For example, in a some embodiments, sender 220generates a radio frequency (RF) signal (or an electromagnetic signalwith another frequency) with an antenna, the signal containinginformation indicating the position of the stylus and/or a status of thestylus. In various embodiments, stylus 220 may include a single sender220 configured to perform one of the functions described above, a singlesender 220 configured to perform multiple functions, or multiple senders220.

FIG. 3 illustrates an example sender 220 that may be used in stylus 200from FIG. 2. The example sender 220 may use frequency divisionmultiplexing to combine the drive signal and data signal into acomposite signal. Sender 220 includes drive signal generator 230 anddata signal generator 240, which are connected to combiner 250. Combiner250 is connected to transmitter 254. Other embodiments utilizing timedivision multiplexing (not shown) may not include combiner 250 and mayinterleave transmission of the drive signal and data signal byalternating between transmission of the drive signal and the datasignal.

In some embodiments, drive signal generator 230 may generate a drivesignal by utilizing a voltage driver. In some embodiments the voltagedriver may generate voltages between 5 to 50 V, though this range is notrequired. In other embodiments, the voltage driver may generate voltagesbetween 12 and 20 V. In a particular embodiment, the voltage driver maygenerate a voltage of approximately 16 V. Data signal generator 240 maygenerate a data signal by modulating a carrier signal with a modulationsignal that contains information indicating a status of stylus 200. Forexample, stylus 200 may encode the drive signal with informationindicating its battery status and/or the amount of pressure on its tip.Stylus 200 may also encode information indicating its orientation, whichmay be based on gyroscopic information, and/or the distance of stylus200 from touch-sensitive area 104, which may be used to determinewhether stylus 200 is in a hover mode. The drive signal and the datasignal may serve as inputs to combiner 250, which may combine the drivesignal and the data signal into a composite signal using, for example,frequency division multiplexing. In alternative embodiments, thecomposite signal may be generated using time division multiplexing.

Combiner 250 may then send the composite signal to transmitter 254,which may transmit the composite signal to touch-sensing device 100 (notshown). In some embodiments this transmission may utilize the capacitiveor inductive touch-sensing elements of touch-sensing device 100described above. For example, a drive signal, now encoded with statusinformation, may be sensed by electrode array 110 (not shown) based on achange in capacitance caused by the drive signal. This receivedcomposite signal may then be processed by one or more receive channelsof touch-sensing device 100 so that the same signal can be used todetermine stylus position information (which can be determined bymeasuring the change in capacitance at a plurality of electrode lines ofelectrode array 110) and the status information (which can be determinedby processing the composite signal as a function of the data signalfrequency). Sending the composite signal in this manner may allow forthe transmission of different types of status information (such as theamount of force exerted on a portion of the stylus, the orientation ofthe stylus, whether a portion of the stylus is within a thresholddistance of a portion of touch-sensing device 100, and/or the status ofa battery) over the same components that are used to detect the positionof the stylus, which may reduce the need for additional transceiverhardware in stylus 200 and touch-sensing device 100. Furthermore, thecomposite signal can be processed simultaneously by two or more receivechannels, which may improve data throughput.

The data signal may have a higher frequency than the drive signal. Forexample, in some embodiments, the drive signal may have a frequencybetween 30 and 300 Hz, though this frequency range is not required. Inother embodiments, the drive signal may have a frequency between 50 and200 Hz. In a particular embodiment, the drive signal may have afrequency of approximately 100 Hz. Furthermore, in some embodiments, thedata signal may have a frequency between 300 Hz and 300 GHz, though thisfrequency range is not required. In other embodiments, the data signalmay have a frequency between 1 KHz and 5 GHz. In a particularembodiment, the data signal may have a frequency of approximately 2.4GHz. In some embodiments, the frequency of the data signal may be atleast twice the frequency of the drive signal frequency. The higherfrequency of the data signal may allow for transmission of largerquantities of data that may be used to communicate the status of stylus200. The higher frequency of the data signal may also allow fortransmission of the data signal via the same electrode array used todetermine stylus position without disrupting the normal operation of thetouch sensor.

FIG. 4 illustrates an example touch-sensing device 100 that may be usedin touch-sensing system 20 from FIG. 1. Touch-sensing device 100includes electrode array 110, measurement circuit 150, controller 174,processor 176, receiver 180, and memory 190. As shown in FIG. 4,electrode array 110 is connected to measurement circuit 150 andcontroller 174, which are both connected to processor 176. Processor 176may also be connected to receiver 180 and memory 190. Receiver 180 mayreceive signals from a different medium or using different techniquesfrom those involving electrode array 110, described above. Someembodiments may have multiple receivers 180, while others may notinclude receiver 180.

Touch sensor 108 and controller 174 may detect the presence and locationof a touch or the proximity of an object within a touch-sensitive areaof touch sensor 108. Herein, reference to a touch sensor may encompassboth the touch sensor and its controller, where appropriate. Touchsensor 108 includes one or more touch-sensitive areas. In someembodiments, touch sensor 108 may include electrode array 110 (shown inFIG. 6). Electrode array 110 may be a plurality of electrode lines,which may be drive and sense electrodes (or an array of electrodes of asingle type), disposed on one or more substrates, which may be made of adielectric material. Herein, an electrode line may refer to a singleconductive wire, a series of electrodes position in a line, or any othersuitable electronic structure or series of electronic structuresdefining a line shape or other pattern. Such electrode lines may operateto detect finger and/or stylus position by mutual capacitance, selfcapacitance, induction, or any other suitable method of positiondetection. Herein, reference to an electrode array may encompass boththe electrodes of the touch sensor as well as the substrate(s) on whichthey are disposed. An electrode (whether a ground electrode, a guardelectrode, a drive electrode, or a sense electrode) may be an area ofconductive material forming a shape, such as for example a disc, square,rectangle, thin line, loop, other suitable shape, or suitablecombination of these. In some embodiments, one or more cuts in one ormore layers of conductive material may create the shape of an electrode,and the area of the shape may be bounded by those cuts. Furthermore,touch sensors, electrode arrays, and electrode lines may be referred toas generating and/or sending a signal. In such cases, while the signalitself may be produced as a result of physical changes in the touchsensor or components of the touch sensor, the generation of the signalmay be driven by the electrode array itself, the controller, and/orother components of touch-sensing device 100.

Measurement circuit 150 may include circuitry configured to processsignals received by electrode array 110. The output of measurementcircuit 150 may then be passed to processor 176 for further analysis,and the resulting information may be stored in memory 190. Memory 190also stores instructions that may be operable to, when executed byprocessor 176, direct the operation of controller 174 and perform otheroperations. Controller 174 may be configured to control the operation ofelectrode array 110. For example, controller 174 may control thegeneration and/or sending of signals by electrode array 110. In someembodiments, controller 174 may control the generation and/or sending ofa composite signal including a data signal and a drive signal byelectrode array 110. Controller 174 may also control the detection ofsignals by electrode array 110 and/or measurement circuit 150.

Measurement circuit 150 and controller 174 may each contain multipleelectronic structures on one or more chips. In some embodiments,measurement circuit 150 and controller 174 may be included in a singlechip or other structure. Various operations of measurement circuit 150and controller 174 may be controlled by hardware or by software storedin memory 190 or another memory device of touch-sensing device 100.

FIG. 5 illustrates an example electrode array 110 that may be used intouch-sensing device 100 from FIG. 4. Electrode array 100 includeselectrode lines 120 and electrode lines 130. Electrode lines 120 and 130may be drive and/or sense lines. Controller 174 may control theoperation of electrode lines 120 and 130 such that each electrode linemay operate as a drive line at one time and as a signal line at anothertime.

As shown in FIG. 5, in some embodiments, electrode lines 120 and 130form a grid pattern, and electrode lines 120 may be orthogonal toelectrode lines 130. In other embodiments, electrode lines 120 and 130may have other orientations and layouts. For example, electrode lines120 may be curved, zigzagged, randomized, or have different orientationsfrom one another, as may electrode lines 130. Furthermore, certainembodiments may include multiple electrode arrays disposed in multiplelayers, or electrode lines 120 may be disposed in a first layer whileelectrode lines 130 are disposed in a second layer.

FIG. 6 illustrates an example measurement circuit 150 that may be usedin touch-sensing device 100 from FIG. 4. Measurement circuit 150 mayprocess the frequency division multiplexed composite signal generated bysender 220 from FIG. 3. As shown in FIG. 6, measurement circuit 150includes electrode array connection 151, which is connected to electrodearray 110. Electrode array connection 151 is connected to receivechannel 152 and receive channel 153.

Receive channel 152 may be used to process the composite signal todetermine the position of stylus 200 or a user's finger. Receive channel153 may be used to process the composite signal to determine thestylus's status information, which may include, for example, the amountof force exerted on a portion of the stylus, the orientation of thestylus, information indicating if a portion of the stylus is within athreshold distance of a portion of touch-sensing device 100, and/or thestatus of a battery. The output of receive channels 152 and 153 may beconnected to processor 176.

Receive channels 152 and 153 may allow touch-sensing device 100 tosimultaneously process a composite signal received by electrode array110 (not shown) in order to determine position information and statusinformation in parallel. Because the signal received by the electrodelines of electrode array 110 contains both the lower frequency drivesignal and the higher frequency data signal, receive channel 152 cananalyze the changes in capacitance caused by the drive signal anddetected at the various electrode lines of electrode array 110 in orderto determine the position of stylus 200, while receive channel 153 cananalyze the higher frequency information that may be encoded in the samesignal to determine the status information of stylus 200. Thus, in someembodiments, touch-sensing device 20 may be able to determine theposition of stylus 20 by analyzing the composite signal as a function ofthe first frequency and determine the information indicating the statusof stylus 20 by analyzing the composite signal as a function of thesecond frequency.

As shown in FIG. 6, receive channel 152 may include switch 154,integrator 155, ADC 160, and signal processor 162. Integrator 155includes capacitor 156 and op-amplifier 158. Switch 154 is connected tocapacitor 156 and the inverting input of op-amplifier 158, and thenon-inverting input of op-amplifier 158 may be connected to ground 159.The output of op-amplifier 158 is connected to capacitor 156 and toanalog-to-digital converter (ADC) 160, which is connected to signalprocessor 162. Integrator 155 may be used to detect the drive signalcomponent of the composite signal as received by electrode array 110,generating at its output a voltage proportional to the capacitance ofone or more electrode lines of electrode array 110. By processing thesignal received by each of the electrode lines of electrode array 110,touching sensing device can determine the position of stylus 200 or auser's finger. For example, the change in capacitance is greater atintersections of electrode lines 120 and 130 that are closer to the tipof stylus 200 or a user's finger. By analyzing the change in capacitanceof the various electrodes, touch-sensing device 100 can thus determinethe position of stylus 200 or a finger.

As shown in FIG. 6, receive channel 153 may include low noise amplifier(LNA) 164, mixer 168, mixer input connection 166, filter 170, and signalprocessor 172. Electrode array connection 151 is connected to LNA 164.The output of LNA 164 is connected to mixer 168, which is also connectedto mixer input connection 166. The output of mixer 168 is connected tofilter 170, which is connected to signal processor 172. Receive channel152 may be used to demodulate the data signal component of the compositesignal and determine the information indicating the status of thestylus. The composite signal can be processed by receive channel 153 inparallel with the processing of receive channel 152, which may allow forgreater data throughput. In certain embodiments, decoding the datasignal in a separate channel using demodulating techniques, rather thanutilizing integrator 155 to decode the data signal, may make the systemless prone to noise.

FIG. 7 illustrates an example stylus 200 and electrode array 110 thatmay be used in touch-sensing system 20 from FIG. 1. Electrode array 110has electrode lines 120 and 130. Electrode lines 120 a and 120 b formelectrode line pair 122, and electrode lines 130 a and 130 b formelectrode line pair 132. As shown in FIG. 7, Stylus 200 has a position140 with respect to electrode array 110. Position 140 has an X-positionalong dimension 142 between electrode lines 120 a and 120 b and aY-position along dimension 144 between electrode lines 130 a and 130 b.Signals sent by electrode line pairs 122 and 132, as well as otherelectrode line pairs formed by other electrode lines 120 and 130, may bedetected by stylus 200 and used to determine position 140.

In some embodiments, electrode lines 120 a and 120 b may generate and/orsend quadrature signals. For example, electrode lines 120 a and 120 bmay send a first signal and a second signal, respectively, each signalhaving the same strength and same frequency, but with the second signalhaving a quadrature phase shift relative to the first signal. Stylus 200may measure the signals sent by electrode line pair 122, detecting thestrength of the first signal and the second signal. The relativestrengths of these signals, as received by stylus 200, may be used todetermine the relative distance of stylus 20 from electrode lines 120 aand 120 b and thereby determine the position of stylus 200 alongdimension 142. This same process may be done in succession by all theelectrode line pairs formed by electrode lines 120.

Furthermore, this process may be repeated with electrode line pair 132and all other electrode line pairs formed by electrode lines 130. Justas the processing of quadrature signals sent by electrode line pair 122was used to determine the position of stylus 200 along dimension 142,processing quadrature signals sent by electrode line pair 132 may allowfor the determination of the position of stylus 200 along dimension 144.Thus, by repeating this process for all electrode line pairs formed byelectrode lines 120 and 130, position 140 of stylus 200 can bedetermined. In some embodiments, stylus 200 may have a near-fieldcoupling mechanism so that only a limited set of signals from electrodeline pairs will be received.

In certain embodiments, stylus 200 may be configured to process thequadrature signals sent by the electrode line pairs of electrode array110 and determine its own position, which it may then communicate backto touch-sensing device 100. In other embodiments, stylus 200 may beconfigured to detect the strengths of the received signals andcommunicate the strengths of the signals received from each electrodeline back to touch-sensing device 100, at which point touch-sensingdevice 100 may determine the position of stylus 200 based on thisinformation. In both of these embodiments, stylus 200 may communicatethis information back to touch-sensing device 100 by using a separatewireless transmitter to generate a signal that may be received byreceiver 180 (not shown) of touch-sensing device 100, or stylus 200 maycommunicate this information via electrode array 110. Communicating theinformation back to touch-sensing device 100 via electrode array 110 mayutilize the same or similar methods to those described above forgenerating a data signal or a composite signal that can be detected byelectrode array 110 and processed by measurement circuit 150 (notshown). For example, upon sensing quadrature signals sent by anelectrode line pair of electrode array 110, stylus 200 may determineposition and/or status information based on the received signal and thencombine a drive signal and a data signal including the information intoa composite signal (or by otherwise encoding the information on thedrive signal) which would then be received by the touch-sensing devicevia electrode array 110.

Furthermore, in some embodiments, techniques other than quadraturesignaling by electrode line pairs may be utilized to allow stylus 200 todifferentiate the signals received from electrode array 110. Forexample, information distinguishing the electrode lines may be encodedonto the signals. Stylus 200 would then be able to decode theinformation, allowing it to determine which signal was received fromwhich electrode line. Using this information in conjunction with therelative strength of the received signals and/or phase shift informationmay allow the touch-sensor to operate in a finger touch mode only, withrespect to sensing capacitive or inductive changes in touch sensor 108,since stylus position could be detected by stylus 200 itself based onsignals generated by the touch sensor. In other words, finger positioncould be directly detected by touch sensor 108 while stylus position isdirectly detected by stylus 200 and then communicated back totouch-sensing device 100.

In some embodiments, a first electrode line sends a first signal havinga first frequency, and a second electrode line sends a second signalhaving a second frequency. The second signal may have a quadraturephase-shift relative to the first signal. Stylus 200 receives the firstsignal at a first strength and receives the second signal at a secondstrength. Stylus 200 sends a response signal to touch-sensing device100, the response signal based on the first signal and the secondsignal, and the position of stylus 200 is determined based on the firstand the second signal. The position of the stylus may be determinedbased at least on a difference between the first signal strength and thesecond signal strength. Furthermore, a third electrode line may send athird signal having a third frequency, a fourth electrode line may senda fourth signal having a fourth frequency, and the first and secondelectrode lines may be oriented in a first direction while the third andfourth electrode lines are oriented in a second direction, the firstdirection being different from the second direction. The first directionand the second direction may be substantially perpendicular. Indetermining the position of stylus 200, a position along a first axismay be determined based at least on the first signal and the secondsignal, and a position along the second axis may be determined based atleast on the third signal and the fourth signal. In sending the responsesignal to touch-sensing device 100, a transmitter of stylus 200 may sendthe response signal to a wireless receiver of the touch-sensing device,or the response signal may be received by electrode array 110. Theposition of stylus 200 may be determined by stylus 200, and the responsesignal may include information indicating the position of stylus 200.The position of stylus 200 may also be determined by touch-sensingdevice 100, and the response signal may include information indicatingthe first strength and the second strength.

FIG. 8 illustrates example stylus 200 and electrode array 110 that maybe used in touch-sensing system 20 from FIG. 1. As shown in FIG. 8,Stylus 200 has a stylus position 140 with respect to electrode array110. Stylus position 140 is located distance 146 from X-Y position 148,which is an orthogonal projection of stylus position 140 onto the planeof electrode array 110. X-Y position 148 has an X-position alongdimension 142 and a Y-position along dimension 144.

As described above, electrode array 110 may be configured to generateand/or send signals that may be detected by stylus 200. In someembodiments, the signals sent by electrode lines 120 and 130 may beencoded with information that allows stylus 200 to determine itsposition 140 relative to touch-sensing device 100. Encoding techniquesmay include, but are not limited to, spread-spectrum techniques,closed-loop power control, and other suitable techniques for generatinga data signal that is under the noise floor of capacitive, inductive, orother touch-sensing techniques described above. This may ensure that theinformation encoded in the signal sent by electrode array 110 does notinterfere with any of the other touch-sensing operations that may beperformed by touch-sensing device 100 or stylus 200.

In some embodiments, electrode line 120 a may send a signal includinginformation identifying itself as the electrode line sending the signal.This signal may also include information identifying the strength atwhich the signal was generated. Stylus 200 may then receive the signalsent by electrode line 120 a at a particular strength, the differencebetween the strength of the signal as generated and as received beingproportional to the distance between electrode line 120 a and stylus200. This process may be repeated by electrode lines 120 b, 120 c, andother electrode lines 120 in electrode array 110. Furthermore, the sameprocess can be repeated with electrode lines 130 a, 130 b, and otherelectrode lines 130 in electrode array 110. Thus, each electrode line120 and 130 may send a signal to stylus 200, each signal includinginformation identifying which electrode line sent the signal.

Furthermore, in some embodiments, the signal may also includeinformation indicating the strength at which it was sent, while in otherembodiments, touch-sensing device 100 may be configured to generate thesignals at a known predetermined strength. The information identifyingwhich electrode line sent which signal, in conjunction with the strengthat which each of these signals was received by stylus 200, may be usedto calculate the position of stylus 200 along dimensions 142 and 144 andthus X-Y position 148. This information may also be used to determinedistance 146 and thus position 140 of stylus 200.

In some embodiments, stylus 200 may be configured to process the signalssent by electrode lines 120 and 130 and determine its own position,which it may then communicate back to touch-sensing device 100. In otherembodiments, stylus 200 may be configured to communicate the informationindicating which electrode line sent each signal and the strength ofeach signal, as detected by stylus 200, back to touch-sensing device100. In such embodiments, touch-sensing device 100 may then determineposition 140 of stylus 200 based on this information. In both of theseembodiments, stylus 200 may communicate this information back totouch-sensing device 100 by using a separate wireless transmitter togenerate a signal that may be received by receiver 180 (not shown) oftouch-sensing device 100, or stylus 200 may communicate this informationvia electrode array 110. Communicating the information back totouch-sensing device 100 via electrode array 110 may utilize the same orsimilar methods to those described above for generating a data signal orcomposite signal that can be detected by electrode array 110 andprocessed by measurement circuit 150 (not shown). For example, in someembodiments, stylus 200 may receive signals sent by electrode lines 120and 130, the signals encoded with information identifying whichelectrode line sent which signal. Stylus 200 may then send a responsesignal to touch-sensing device 100 via electrode array 110 based on thestrength at which each signal was received and the encoded information.

In some embodiments, a first electrode line of an electrode array sendsa first signal including information identifying the first electrodeline, the first signal having a first strength. The first electrode linesends the first signal to stylus 200. Touch-sensing device 100 thenreceives a received signal from stylus 200, the received signal based atleast in part on the information identifying the first electrode lineand a strength at which the first signal was received by the stylus. Theposition of stylus 200 is then determined based at least in part on theinformation identifying the first electrode line and the strength atwhich the first signal was received by the stylus. The received signalmay include information indicating the strength at which the firstsignal was received by stylus 200 and information identifying the firstelectrode line. The received signal may include information indicatingthe position of the stylus. The first signal may also includeinformation indicating the strength at which the first signal was sentby the first electrode line, and the determination of the position ofstylus 200 may be based further on the difference between the strengthat which the first signal was sent by the first electrode and thestrength at which the first signal was received by the stylus. Theposition of stylus 200 may include a position along a first, second, andthird axes, wherein the first axis is different from the second axis,the first and second axes are substantially parallel to the electrodearray, and the third axis is substantially perpendicular to theelectrode array.

Furthermore, a second electrode line of the electrode array may send asecond signal including information identifying the second electrodeline, and determining the position of stylus 200 may be based further onthe information identifying the second electrode line and a strength atwhich the second signal was received by stylus 200. A third electrodeline of the electrode array may send a third signal includinginformation identifying the third electrode line, and a fourth electrodeline of the electrode array may send a fourth signal includinginformation identifying the fourth electrode line. The first and secondelectrode lines may be oriented in a substantially similar firstdirection, and the third and fourth electrode lines may be oriented in asubstantially similar second, the first direction being different fromthe second direction. The first direction and the second direction maybe substantially perpendicular.

In other embodiments, stylus 200 receives a first signal includinginformation identifying a first electrode line of an electrode array oftouch-sensing device 100, the first signal have a first receivedstrength. Stylus 200 analyzes the first signal to determine the firstreceived strength and the information identifying the first electrodeline. Stylus 200 then generates a first response signal based at leastin part on the first received strength and the information identifyingthe first electrode line and sends the first response signal totouch-sensing device 100. Stylus 200 may receive a second signalcomprising information identifying a second electrode line of theelectrode array, the second signal having a second received strength.The first response signal may be based further on the second receivedstrength and the information identifying the second electrode line, orstylus 200 may generate a second response signal based at least in parton the second received strength and the information identifying thesecond electrode line. The first signal may further include informationindicating a strength at which the first signal was sent by the firstelectrode line. The first response signal may include the position ofstylus 200, and stylus 200 may determine its position based at least inpart on the first received strength, the information identifying thefirst electrode line, the second received strength, and the informationidentifying the second electrode line

Encoded signals generated by touch sensor 108 and received by stylus 200with information used to determine the position of stylus 200 mayimprove the ability of touch sensor 108 to operate without interference.Using methods such as spread spectrum schemes or closed-loop powercontrol may allow stylus 200 to receive signals that remain below thenoise floor of touch sensor 108. The reduced interference of this“water-marking” signaling scheme may improve the ability offinger-sensing and touch-sensing signaling to operate simultaneously.Furthermore, since finger-sensing and stylus-sensing schemes may requiredifferent signaling levels and time budgets for electrode touch sensor108, detecting finger position and stylus position via differentpathways may improve performance of touch-sensing system 20 by obviatingthe need to accommodate their conflicting requirements in the samereceive channel. Since design compromises caused by conflicting timingand signaling requirements of finger-sensing and stylus-sensing may beavoided, these methods may allow for improved performance of bothfinger-sensing and stylus-sensing.

Herein, “or” is inclusive and not exclusive, unless expressly indicatedotherwise or indicated otherwise or indicated otherwise by context.Therefore, herein, “A or B” means “A, B, or both,” unless expresslyindicated otherwise or indicated otherwise by context. Moreover, “and”is both joint and several, unless expressly indicated otherwise orindicated otherwise by context. Therefore, “A and B” means “A and B,jointly or severally,” unless expressly indicated otherwise or indicatedotherwise by context.

This disclosure encompasses all changes, substitutions, variations,alterations, and modifications to the example embodiments herein that aperson having ordinary skill in the art would comprehend. Similarly,where appropriate, the appended claims encompass all changes,substitutions, variations, alterations, and modifications to the exampleembodiments herein that a person having ordinary skill in the art wouldcomprehend. Moreover, reference in the appended claims to an apparatusor system or a component of an apparatus or system being adapted to,arranged to, capable of, configured to, enabled to, operable to, oroperative to perform a particular function encompasses that apparatus,system, component, whether or not it or that particular function isactivated, turned on, or unlocked, as long as that apparatus, system, orcomponent is so adapted, arranged, capable, configured, enabled,operable, or operative.

Various embodiments disclosed herein may be used together in a varietyof combinations. In some embodiments, touch-sensing system 20 may usedifferent types of touch-sensing device 100 and stylus 200, andtouch-sensing device 100 and stylus 200 may have different numbers andtypes of components, as well as different configuration and organizationof those components. For example, in certain embodiments, stylus 200 mayhave different numbers and types of processor 210, sender 220, andreceiver 260, as well as additional components. As another example, invarious embodiments, electrode array 110 may have different types,numbers, and orientations of electrodes lines 120 and 130. For example,in some embodiments, electrode lines 120 and 130 may form a grid ofperpendicular lines, while in other embodiments, electrode lines 120 and130 may different sizes, shapes, and orientations.

Furthermore, in various embodiments, touch-sensing system 20 may utilizeone or more of the communication methods described above to communicateinformation between touch-sensing device 100 and stylus 200 and viceversa. For example, in some embodiments, stylus 200 may receive a signalfrom touch-sensing device 100 that includes encoded information whilealso sending a combined signal including a drive signal and a datasignal to touch-sensing device 100 via electrode array 110. In otherembodiments, stylus 200 may receive quadrature signals from electrodeline pairs 122 and 132 while also sending a combined signal including adrive signal and a data signal to touch-sensing device 100 via electrodearray 110. In still other embodiments, stylus 200 may receive quadraturesignals from electrode line pairs 122 and 132, each quadrature signalencoded with information that may be used by stylus 200 to determineposition and/or other information.

Although the present invention has been described above in connectionwith several embodiments; changes, substitutions, variations,alterations, transformations, and modifications may be suggested to oneskilled in the art, and it is intended that the present inventionencompass such changes, substitutions, variations, alterations,transformations, and modifications as fall within the spirit and scopeof the appended claims.

What is claimed is:
 1. A stylus comprising: a sensor configured toperform operations comprising measuring a first signal strength of afirst signal generated by a first electrode line of an electrode arrayof a touch-sensing device and a second signal strength of a secondsignal generated by a second electrode line of the electrode array ofthe touch-sensing device, the first electrode line and the secondelectrode line being a first electrode line pair of a plurality ofelectrode line pairs of the electrode array and being oriented in afirst direction along a first axis of the electrode array, the secondelectrode line being adjacent to the first electrode line, the firstsignal encoded with information identifying that the first signal wasgenerated by the first electrode line; a signal processor configured toperform operations comprising decoding the information identifying thatthe first signal was generated by the first electrode line anddetermining position information based at least on the informationidentifying that the first signal was generated by the first electrodeline and the first signal and the second signal, the positioninformation comprising an indication of a position of the stylus alongthe first axis of the electrode array, wherein the signal processor isconfigured to determine the position information based at least on adifference between the first signal strength and the second signalstrength, wherein: determining the position information comprising anindication of the position of the stylus comprises determining afirst-dimensional position of the stylus along the first axis based atleast on the first signal and the second signal; and thefirst-dimensional position is a location within a plane of the electrodearray of the touch-sensing device; and a transmitter configured to senda signal comprising the position information to the touch-sensingdevice.
 2. The stylus of claim 1, wherein the first signal comprises anin-phase signal, and the second signal comprises a quadrature-phasesignal.
 3. The stylus of claim 1, wherein the plurality of electrodeline pairs comprises a second electrode line pair oriented in a seconddirection along a second axis of the electrode array, the firstdirection being different from the second direction, the secondelectrode line pair comprising a third electrode line oriented in thesecond direction and a fourth electrode line oriented in the seconddirection, the fourth electrode line being adjacent to the thirdelectrode line.
 4. The stylus of claim 3, wherein: the sensor isconfigured to perform operations comprising measuring a third signalstrength of a third signal generated by the third electrode line and afourth signal strength of a fourth signal generated by the fourthelectrode line; determining the position information comprising anindication of the position of the stylus further comprises determining asecond-dimensional position of the stylus along the second axis based atleast on the third signal of the second electrode line pair and thefourth signal of the second electrode line pair; and the positioninformation indicates at least the first-dimensional position of thestylus along the first axis and the second-dimensional position alongthe second axis.
 5. The stylus of claim 3, wherein the first directionand the second direction are substantially perpendicular.
 6. The stylusof claim 1, wherein the transmitter comprises a wireless transmitterconfigured to send the signal comprising the position information to thetouch-sensing device by performing operations comprising sending thesignal comprising the position information to a wireless receiver of thetouch-sensing device.
 7. The stylus of claim 1, wherein the transmitteris further configured to send the signal comprising the positioninformation to the touch-sensing device via the electrode array of thetouch-sensing device.
 8. The stylus of claim 1, wherein the positioninformation comprises the first signal strength and the second signalstrength, and wherein the touch-sensing device further comprises aposition-calculating module configured to determine a position of thestylus based on the position information.
 9. A non-transitorycomputer-readable medium comprising logic, the logic when executed by aprocessor configured to cause the processor to perform operationscomprising: accessing a first signal strength of a first signal receivedby a stylus and generated by a first electrode line of an electrodearray of a touch-sensing device, the first signal strength of the firstsignal measured by the stylus, the first signal having a firstfrequency; accessing a second signal strength of a second signalreceived by the stylus and generated by a second electrode line of theelectrode array of the touch-sensing device, the second signal strengthof the second signal measured by the stylus, the first electrode lineand the second electrode line being oriented in a first direction alonga first axis of the electrode array, the second electrode line beingadjacent to the first electrode line, the first signal encoded withinformation identifying that the first signal was generated by the firstelectrode line; decoding the information identifying that the firstsignal was generated by the first electrode line; and determining aposition of the stylus based on the information identifying that thefirst signal was generated by the first electrode line and the firstsignal and the second signal, wherein the position of the stylus isdetermined based at least on a difference between the first signalstrength and the second signal strength, and wherein determining theposition of the stylus comprises determining, based at least on thefirst signal and the second signal, a first-dimensional position of thestylus along the first axis, wherein the first-dimensional position is alocation within a plane of the electrode array of the touch-sensingdevice.
 10. The non-transitory computer-readable medium of claim 9,wherein the second signal has a quadrature phase-shift relative to thefirst signal.
 11. The non-transitory computer-readable medium of claim9, wherein the operations further comprise: accessing a third signalstrength of a third signal received by the stylus and generated by athird electrode line of the electrode array, the third signal having athird frequency; and accessing a fourth signal strength of a fourthsignal received by the stylus and generated by a fourth electrode lineof the electrode array, the fourth signal having a fourth frequency;wherein the third and fourth electrode lines are oriented in a seconddirection along a second axis of the electrode array, and wherein thefirst direction is different from the second direction.
 12. Thenon-transitory computer-readable medium of claim 11, wherein determiningthe position of the stylus comprises determining, based at least on thethird signal and the fourth signal, a second dimensional position of thestylus along the second axis.
 13. The non-transitory computer-readablemedium of claim 11, wherein the first direction and the second directionare substantially perpendicular.
 14. The non-transitorycomputer-readable medium of claim 9, wherein the operations furthercomprise controlling the stylus to send, by a wireless transmitter ofthe stylus, a response signal to a wireless receiver of thetouch-sensing device, the response signal comprising informationindicating the position of the stylus.
 15. The non-transitorycomputer-readable medium of claim 9, wherein the operations furthercomprise controlling the stylus to send a response signal to thetouch-sensing device via the electrode array of the touch-sensingdevice, the response signal comprising information indicating theposition of the stylus.
 16. The non-transitory computer-readable mediumof claim 9, wherein the operations further comprise controlling thestylus to send a response signal to the touch-sensing device, theresponse signal comprising information indicating the first strength andthe second strength, the touch-sensing device being configured todetermine the position of the stylus based on the position information.17. The stylus of claim 1, wherein: the first signal generated by thefirst electrode line comprises information distinguishing the firstelectrode line from the second electrode line; and the stylus isconfigured to determine the information distinguishing the firstelectrode line from the second electrode line.
 18. The non-transitorycomputer-readable medium of claim 9, wherein: the first signal generatedby the first electrode line comprises information distinguishing thefirst electrode line from the second electrode line; and the operationsfurther comprise determining the information distinguishing the firstelectrode line from the second electrode line.
 19. A method, comprising:accessing, by a processor, a first signal strength of a first signalreceived by a stylus and generated by a first electrode line of anelectrode array of a touch-sensing device, the first signal strength ofthe first signal measured by the stylus, the first signal having a firstfrequency; accessing, by the processor, a second signal strength of asecond signal received by the stylus and generated by a second electrodeline of the electrode array of the touch-sensing device, the secondsignal strength of the second signal measured by the stylus, the firstelectrode line and the second electrode line being oriented in a firstdirection along a first axis of the electrode array, the secondelectrode line being adjacent to the first electrode line, the firstsignal encoded with information identifying that the first signal wasgenerated by the first electrode line; decoding the informationidentifying that the first signal was generated by the first electrodeline; and determining, by the processor, a position of the stylus basedon the information identifying that the first signal was generated bythe first electrode line and the first signal and the second signal,wherein the position of the stylus is determined based at least on adifference between the first signal strength and the second signalstrength, and wherein determining the position of the stylus comprisesdetermining, based at least on the first signal and the second signal, afirst-dimensional position of the stylus along the first axis, whereinthe first-dimensional position is a location within a plane of theelectrode array of the touch-sensing device.